novaplace wrote:This is the output of the "LS" command, but I find no "boot" as in indicated various articles I'm reading... Maybe it's because it's encrypted?

Indirectly. / is encrypted, so there must be a separate unencrypted partition for /boot. As its is mounted on /boot, the partition does not contains a boot/ directory but the contents of /boot : efi/ (empty, mount point for the EFI partition), grub/ (contains runtime GRUB files), kernel images, initramfs...

(hd0,gpt1) is obviously an EFI partition and it seems that the /boot partition is (hd0,gpt2). I guess that (hd0,gpt3) is the encrypted partition.Does (hd0,gpt2)/grub contain a grub.cfg file ?What does the command "set" report about prefix and root ?What happens if you run the command "normal" ?

1) the grub prompt is a normal one (not a rescue one).2) does (hd0,gpt2)/grub contain a grub.cfg file? - I'm not sure how to find this out. I'm new to all this.4) "normal" seems as though it is accepted, but nothing changes on reboot - still stuck at the grub prompt.3) the "set" command reports the following:

Normally, I have exited the grub menu by typing reboot, to see if helped get the system operational again.

This time, I happened to type "exit" to which is dumped me into my normal graphical boot menu which times out and loads my regular debian gnome environment. It prompted me for my encryption passphase which it accepted, and I'm now booted into my normally working system.

What does this tell us, is this repeatable, and what do I need to do inside my working system in order to repair this? Do I need to do another apt-get update and then apt-get upgrade?

Yes, I have backed up data since I've been booted. I've also since rebooted, and each time I reboot, I end up in the grub2 normal (not rescue) prompt. I type "exit" and it gives me my normal grub gui screen (that looks similar to http://media.tutorialforlinux.com/debian/9Stretch/installation/994-grubSplash.jpg, this is not mine). The boot proceeds normally from that grub gui screen. Everything works normally once booted.

So, I think it's a configuration issue only that drops me into the grub prompt first instead of the the grub gui screen. Does that help? What should I try in order to remedy this?